JPH0818318A - Glass antenna for automobile - Google Patents

Abstract

PURPOSE:To provide the glass antenna for automobile which has a high antenna gain and a low noise to AM radio reception. CONSTITUTION:This glass antenna consists of a window glass 1 for automobile, a defogger 3 formed in this window glass 1, and an antenna conductor 2 whose one end is directly or indirectly connected to a radio receiver 7. The defogger 3 is earthed by a capacitor 10 with respect to high frequency, and only the antenna conductor 2 is used for reception in the case of AM radio reception frequencies. A capacity C2 between the antenna conductor 2 and a body 9 is set to <=50pF to realize the glass antenna for automobile which has a high antenna gain (S) and a low noise (N) and has a very efficient AM radio reception sensitivity (S/N) characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a window glass of an automobile,
The present invention relates to a glass antenna for an automobile that receives a radio broadcast by providing a defogger of an electric heating type and an antenna conductor.

[0002]

2. Description of the Related Art As a radio antenna for an automobile, an antenna conductor for AM, FM or both AM and FM is provided on the interior surface of a glass plate for automobile windows as an alternative to a rod antenna or a whip antenna. Glass antennas are widely used. Since this glass antenna does not project to the outside, it does not pose a danger, it does not break, and it does not rust, so there is little change in performance and it makes the exterior design of the car good. It has the advantage of

AM using a conventional automobile glass antenna
As a glass antenna system for an automobile that also serves as an FM, the one shown in FIG. 6 is known.

In FIG. 6, 1 is a glass plate for a rear window of an automobile, 14 is an antenna conductor, 3 is a defogger, 4, 4a,
4b is a bus bar, 5 is a terminal portion of the antenna conductor 14, 6 is a feeder, 7 is a radio receiver, 8 is a power source, 9 is a car body (ground), 10 is a capacitor, C ₁ is a defogger 3 and a car body 9 , C ₃ is a capacitance existing between the antenna conductor 14 and the vehicle body 9, Mf is an electromagnetic coupling, and Cf is an electrostatic coupling.

In the conventional automobile glass antenna shown in FIG. 6, an antenna conductor 14 is provided above a defogger 3 of the electric heating type of a window glass plate 1 of an automobile, and the defogger 3 further includes bus bars 4, 4a and 4b. The bus bar 4a is grounded to the body 9 of the automobile at a high frequency by a capacitor 10, and the antenna conductor 14 has a terminal portion 5 which is connected via a feeder 6 to a radio receiver. Connected to 7. Here, the defogger 3 and the antenna conductor 14 of the electric heating type are both FM
It resonates at the radio reception frequency, but does not resonate at the AM radio reception frequency.

At the FM radio reception frequency, the energization heating type defogger 3 and the antenna conductor 14 are electromagnetically coupled Mf and electrostatically coupled Cf to operate as an antenna.

Since the defogger 3 and the antenna conductor 14 are arranged in a positional relationship such that the degree of coupling is almost a critical coupling, and a state of multiple resonance is formed, the defogger 3 and the antenna conductor 14 are viewed from the terminal portion 5. The frequency band characteristic becomes both characteristics, and a wide band characteristic can be obtained. Because of this, F
The antenna and the feeder 6 can be matched over the entire band of the M radio reception frequency, and FM radio reception is performed.

Regarding the electromagnetic coupling Mf, the degree of coupling is changed depending on the distance and relative positional relationship between the defogger 3 and the antenna conductor 14. For the electrostatic coupling Cf, see Defogger 3
The degree of coupling changes depending on the magnitude of the coupling capacitance formed by the and the part of the antenna conductor 14 and the coupling positional relationship. Further, since the bus bar 4a of the defogger 3 is grounded at a high frequency by the capacitor 10, the noise from the power source 8 can be controlled.

At the AM radio reception frequency, only the antenna conductor 14 operates as an antenna. This is because the length of both the antenna conductor 14 and the defogger 3 is extremely short as compared with the wavelength of the AM radio reception frequency, and the bus bar 4b at one end of the defogger 3 is grounded to the body 9 of the automobile. The potential is almost the same as that of the body 9 of the automobile, so that there is no electrical coupling between the antenna conductor 14 and the defogger 3, and only the antenna conductor 14 operates as an antenna. Therefore, it is possible to control the noise inflow from the power supply 8 to the antenna conductor 14 even in the AM radio reception.
Further, in order to reduce the stray capacitance of the antenna conductor 14, the shape and arrangement of the antenna conductor 14 are determined at a distance of 3 cm or more from the vehicle body 9 and the defogger 3, and AM radio reception is performed.

[0010]

However, the above-mentioned conventional glass antenna for automobiles has a problem that sufficient AM radio reception sensitivity (S / N ratio) cannot be obtained.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a glass antenna for a vehicle is connected to a window glass of the vehicle, a defogger formed on the window glass and electrically heated, and one end thereof is directly or indirectly connected to a radio receiver. A glass antenna for an automobile, which includes an antenna conductor and a capacitor and an inductor part installed between the defogger and the body of the automobile, and receives an AM radio reception frequency only by the antenna conductor. The capacitance between the bodies is set to 50 pF or less.

[0012]

With this structure, a glass antenna for a vehicle having a high antenna gain (S) and a low noise (N) in AM radio reception is realized while ensuring all the advantages of the conventional glass antenna system for a vehicle. .

[0013]

Embodiments of the present invention will be described below with reference to FIGS. It should be noted that the same components as those of the related art will be denoted by the same reference numerals and detailed description will be omitted.

The glass antenna for an automobile of the present invention shown in FIG. 1 has a plurality of heater wires on a glass plate 1 for an automobile window.
An energization heating type defogger 3 having opposing bus bars 4, 4a, 4b connected to both ends of the heater wire group is provided. An example of this defogger 3 is to print a conductive silver paste on the inner surface of a glass plate in the lateral direction with a large number of thin electric heating heater wires at substantially parallel intervals.
The defogger 3 is an electrically heated type formed by baking.
Then, as shown in the figure, one of the bus bars of the defogger 3, for example, one bus bar on one side is vertically divided into two, one bus bar 4b is directly grounded to the body 9 of the automobile, and the other bus bar 4a is a power source. At the same time, it is grounded to the body 9 of the automobile through a capacitor 10 at a high frequency. This Defogger 3 above
The antenna conductor 2 is provided above the antenna conductor 2, and the antenna conductor 2 includes a terminal portion 5, and the terminal portion 5 is connected to a radio receiver 7 via a feeder 6. Further, both the energization heating type defogger 3 and the antenna conductor 2 resonate at the FM radio reception frequency, but do not resonate at the AM radio reception frequency.

At the FM radio reception frequency, the energization heating type defogger 3 and the antenna conductor 2 are electromagnetically coupled Mf and electrostatically coupled Cf. Then, the defogger 3 and the antenna conductor 2 are arranged in a positional relationship such that the degree of coupling becomes substantially critical coupling, and a state of multiple resonance is formed.

Regarding the electromagnetic coupling Mf, the degree of coupling is changed depending on the distance and relative positional relationship between the defogger 3 and the antenna conductor 2. Regarding the electrostatic coupling Cf, the degree of coupling is changed depending on the magnitude of the coupling capacitance formed by the defogger 3 and a part of the antenna conductor 2 and the coupling positional relationship.

At the AM radio reception frequency, only the antenna conductor 2 operates as an antenna. The feature of the present embodiment is that the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile is further specified in the above-mentioned configuration as described later.

In another embodiment of the present invention shown in FIG. 2, a large number of heater wires are provided on a window glass plate 1 of an automobile, and opposed bus bars 4, 4c connected to both ends of the group of heater wires. The defogger 3 of the electric heating system is provided. This defogger 3 is a defogger of the electric heating type formed by printing and baking a conductive silver paste in which a large number of thin electric heating heater wires are printed in a lateral direction on the inner surface of a glass plate at substantially parallel intervals. . As shown in the drawing, FM choke coils 11a and 11b are provided between the opposing bus bars 4 and 4c of the defogger 3 and the power source 8 of the defogger 3, and are insulated from the power source 8 in the FM radio reception frequency region. . The antenna conductor 2 is provided above the defogger 3, and the antenna conductor 2 includes a terminal portion 5.
This terminal portion 5 is connected to a radio receiver 7 via a feeder 6.

Further, both the energization heating type defogger 3 and the antenna conductor 2 resonate at the FM radio reception frequency, but do not resonate at the AM radio reception frequency.

At the FM radio reception frequency, the energization heating type defogger 3 and the antenna conductor 2 are electromagnetically coupled Mf and electrostatically coupled Cf. Then, the defogger 3 and the antenna conductor 2 are arranged in a positional relationship such that the degree of coupling becomes substantially critical coupling, and a state of multiple resonance is formed.

Regarding the electromagnetic coupling Mf, the degree of coupling is changed depending on the distance and relative positional relationship between the defogger 3 and the antenna conductor 2. Regarding the electrostatic coupling Cf, the degree of coupling is changed according to the magnitude of the coupling capacitance formed by the defogger 3 and a part of the antenna conductor 2 and the coupling positional relationship.

At the AM radio reception frequency, only the antenna conductor 2 operates as an antenna. The embodiment of FIG. 2 is also characterized in that the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile is specified as described later, like the embodiment of FIG.

Here, the antenna conductors shown in FIGS. 1 and 2 are shown as an example provided above the defogger of the glass plate for automobiles, but the invention is not limited to this, and may be provided above and below the defogger, respectively. Alternatively, it may be provided in another margin. Further, as the antenna conductor, in the same manner as the heater wire of the defogger described above, it is common to use a line-type print type in which a conductive silver paste is printed and baked on a glass plate surface in a predetermined pattern. The antenna conductor is not limited to a transparent conductive film or an ultrafine conductive wire, and may be an antenna conductor. Further, at the FM radio reception frequency, the defogger of the electric heating method and the antenna conductor are electromagnetically coupled and electrostatically coupled, and the defogger and the antenna conductor are arranged in a positional relationship such that the degree of coupling is substantially critical coupling. Although the example of forming multiple resonance is shown, the position is not limited to this and the position where the defogger of the electric heating method and the antenna conductor are electromagnetically or electrostatically coupled and the degree of coupling becomes almost critical coupling. In relation, the defogger and the antenna conductor may be arranged to form a double resonance state.

The operation of the embodiment of FIGS. 1 and 2 configured as above will be described. 1 and 2, at the FM radio reception frequency, the defogger 3 of the electric heating system and the antenna conductor 2 are electromagnetically coupled Mf and electrostatically coupled Cf to operate as an antenna. Since the defogger 3 and the antenna conductor 2 are arranged in a positional relationship such that the degree of coupling is almost critical coupling, and a multi-resonance state is formed, the frequency band characteristic viewed from the terminal portion 5 of the antenna conductor 2 is shown. Has both characteristics, and a wide band characteristic can be obtained. Therefore, the antenna and the feeder 6 can be matched over the entire FM radio reception frequency band, and FM radio reception is performed. In particular, in the case of FIG. 1, since the bus bar 4a of the defogger 3 is grounded at a high frequency by the capacitor 10, the noise from the power source 8 can be controlled.

On the other hand, at the AM radio reception frequency, only the antenna conductor 2 operates as an antenna to perform AM radio reception. This is because the lengths of the antenna conductor 2 and the defogger 3 are both extremely short compared to the wavelength of the AM radio reception frequency, and the bus bar 4b at one end of the defogger 3 is grounded to the body 9 of the automobile. Is almost the same potential as the body 9 of the automobile. Therefore, it is possible to control the noise flow from the power supply 8 to the antenna conductor 2 even in the AM radio reception.

In another embodiment of the present invention shown in FIG. 3, a large number of heater wires are provided on a glass plate 1 for an automobile window, and opposed bus bars 4, 4a, 4 connected to both ends of the heater wire group.
An electric heating type defogger 3 having b and b is provided. This electric heating type defogger 3 is formed by printing a large number of thin electric heating heater wires in a lateral direction on the inner surface of a glass plate with a conductive silver paste substantially parallel to each other at intervals and baking them. Is the defogger. Then, as shown in the figure, one of the bus bars of the defogger 3, for example, one bus bar on one side is vertically divided into two parts, one bus bar 4b is directly grounded to the body 9 of the automobile, and the other bus bar 4a is an inductor. It is connected to the power supply 8 via a noise filter 13 composed of components and a capacitor.

Further, as in the defogger, one bus bar is provided on each of the left and right sides instead of being divided into two parts, and one is connected to the power supply circuit side and the other is connected to the body of the automobile so that the current from the power supply circuit is supplied. It may flow in one direction.

An antenna conductor 2 is provided above the defogger 3, and the antenna conductor 2 has a terminal portion 5. The terminal portion 5 is connected to a radio receiver 7 via a preamplifier 12 and a feeder 6. It is connected.

The other embodiment is also characterized in that the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile is specified as will be described later, as in the embodiment shown in FIGS. .

Here, although the antenna conductor shown in FIG. 3 is shown as an example provided above the defogger of the window glass of the automobile, the invention is not limited to this, and may be provided above and below the defogger, respectively. Alternatively, it may be provided in another margin.
Further, as the antenna conductor, in the same manner as the heater wire of the defogger described above, it is common to use a line-type print type in which a conductive silver paste is printed and baked on a glass plate surface in a predetermined pattern. The antenna conductor is not limited to a transparent conductive film or an ultrafine conductive wire, and may be an antenna conductor.

Then, the antenna conductor 2 operates as an antenna for AM and FM, and the antenna conductor 2 and the radio receiver 7
The pre-amplifier 12 is inserted in a good portion between and to perform AM and FM radio reception. In addition, since the bus bar 4b at one end of the defogger is grounded to the body 9 of the automobile, the defogger 3 has almost the same potential as the ground, so that the noise inflow from the power supply circuit 8 to the antenna conductor 2 can be controlled.

In the present invention, in the configuration of the embodiment shown in FIGS. 1 to 3, the capacitance C ₂ formed between the antenna conductor 2 and the vehicle body 9 and the AM radio reception sensitivity (S / N ratio).
(Table 1) shows the experimental results of the relationship between the two when the capacitance C ₁ between the defogger 3 and the body 9 of the automobile is constant (50 pF).

[0033]

[Table 1]

As is apparent from FIG. 4 which is a characteristic diagram of (Table 1), the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile is shown.
AM radio reception sensitivity (S / N ratio) started to rise at 50 pF or less, and it was found that the AM radio reception sensitivity (S / N ratio) can be improved efficiently by setting the capacitance C ₂ value to be less than this capacity. .

Further, in the range where the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile is 25 pF or less, the AM radio reception sensitivity (S / N ratio) starts to increase dramatically, and the capacitance C ₂ is 60 pF or more. A very effective improvement of at least double or more was obtained compared to the AM radio reception sensitivity (S / N ratio).

[0036] Here, in motor vehicles having a capacitance C ₁ values between the defogger 3 and the capacity C ₁ values between the body 9 of the motor vehicle is mentioned only for automobile 50 pF, this defogger 3 except the vehicle body 9 The same result was obtained.

The setting method of the capacitance C ₂ value between the antenna conductor 2 and the body 9 of the automobile to the above-mentioned optimum range is the patterning in which the facing area between the antenna conductor 2 and the automobile body 9 is changed in each of the above embodiments. Although the case has been illustrated, the adjustment can be made by any of the distance between the two, the facing length, and the dielectric constant.

As described above, according to the above-described embodiment, the high antenna gain (S) for AM radio broadcasting is maintained without impairing the advantage of efficient FM radio reception, which is the advantage of the conventional automobile glass antenna system. ), A low noise (N), and a very efficient AM radio reception sensitivity (S / N ratio) can be realized.

Since the constituent members are the same as the conventional constituent members, a very simple structure and a low cost can be achieved.

FIG. 5 is also a schematic view of an automobile glass antenna showing another embodiment of the present invention. Explaining the mechanism below, the automobile glass antenna of the present invention shown in FIG. 5 is used for automobile windows. The glass plate 1 is provided with an energization heating type defogger 3 having a large number of heater wires and opposing bus bars 4, 4a, 4b connected to both ends of the heater wire group. An example of the defogger 3 of the electric heating method is formed by printing a large number of thin electric heating heater wires in the lateral direction on the inner surface of the glass plate 1 at intervals substantially in parallel and baking the conductive silver paste. It is a defogger 3 of an electric heating type. As shown in the figure, one of the bus bars of the defogger 3, for example, one of the bus bars is vertically divided from a desired position. One bus bar 4b is directly grounded to the body 9 of the automobile and the other is directly connected to the power source 8. It is connected.

Further, as in the defogger, one bus bar is provided on each of the left and right sides instead of being divided into two parts, and one is connected to the power source side and the other is connected to the body of the automobile so that the current from the power source is unidirectional. You may make it flow to.

An antenna conductor 2 is provided above the defogger 3, and the antenna conductor 2 has a terminal portion 5. The terminal portion 5 is connected to a radio receiver 7 via a preamplifier 12 and a feeder 6. It is connected.

Here, although the antenna conductor shown in FIG. 5 is shown as an example provided above the defogger of a glass plate for automobile windows, the invention is not limited to this, and may be provided above and below the defogger, respectively. Alternatively, it may be provided in another margin.
Further, as the antenna conductor, in the same manner as the heater wire of the defogger described above, it is common to use a line-type print type in which a conductive silver paste is printed and baked on a glass plate surface in a predetermined pattern. The antenna conductor is not limited to a transparent conductive film or an ultrafine conductive wire, and may be an antenna conductor.

The antenna conductor 2 operates as an antenna for AM and FM, and the antenna conductor 2 and the radio receiver 7
The pre-amplifier 12 is inserted in a good portion between and to perform AM and FM radio reception. Also, Defogger 3
Since the bus bar 4b at one end is grounded to the body 9 of the automobile, the defogger 3 has almost the same potential as the ground, so that noise inflow from the power supply 8 to the antenna conductor 2 can be controlled.

Also in the above embodiment, the relationship between the capacitance C ₂ between the antenna conductor 2 and the body 9 of the automobile and the AM radio reception sensitivity (S / N ratio) is the same as in (Table 1) and FIG. confirmed.

[0046]

As described above, the glass antenna for an automobile according to the present invention has a window glass for an automobile, a defogger formed on the window glass and electrically heated, and one end of which is directly or indirectly connected to a radio receiver. A glass antenna system for an automobile, characterized by comprising: an antenna conductor, and a capacitor and an inductor part installed between the defogger and a car body, and receiving only with the antenna conductor at an AM radio reception frequency. , By setting the capacitance between the body and the antenna conductor to 50 pF or less,
AM radio reception sensitivity (S / N ratio) characteristics can be improved. Further, when the capacitance value is 25 pF or less, the AM radio reception sensitivity can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of a glass antenna for an automobile of the present invention.

FIG. 2 is a schematic diagram of another embodiment.

FIG. 3 is a schematic diagram of another embodiment.

FIG. 4 shows the capacitance A between the antenna conductor and the body of the car.
Characteristic diagram showing the relationship between M radio reception sensitivity (S / N ratio)

FIG. 5 is a schematic view of another embodiment.

FIG. 6 is a schematic diagram of a conventional automotive glass antenna system.

[Explanation of symbols]

1 Automotive Glass Plate 2 Antenna Conductor 3 Defogger 7 Radio Receiver 9 Car Body 10 Capacitor C ₂ Capacitance between Antenna Conductor 2 and Car Body 9

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Rikitake 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A windowpane for an automobile, a defogger formed on the windowpane that is electrically heated, and an antenna conductor whose one end is directly or indirectly connected to a radio receiver.
A capacitor installed between the defogger and the body,
Alternatively, in a glass antenna system for an automobile, which comprises an inductor component, or a capacitor and an inductor component, and receives only the antenna conductor at an AM radio reception frequency, a capacitance between the body of the automobile and the antenna conductor is 50 pF. A glass antenna for an automobile, which is set as follows. 2. The glass antenna for an automobile according to claim 1, wherein the electrically heated defogger is directly connected to the body of the automobile. 3. The glass antenna for an automobile according to claim 1, wherein the capacitance between the antenna conductor and the body of the automobile is 25 pF or less.